Study Questions:

What is the impact of implantable cardioverter-defibrillators (ICDs) on mortality in patients with left ventricular assist devices (LVADs)?

Methods:

The study investigators used PubMed and OVID databases to identify studies with the following inclusion criteria: 1) these were randomized controlled trials or observational studies; 2) they compared LVAD-supported patients with ICDs to those without ICDs; 3) they reported information for all-cause mortality for both ICD and no-ICD groups; and 4) they reported the estimate of (RR) with 95% confidence interval (CI), or different measures of RR such as hazard ratio or odds ratio, or they provided data such that RR could be calculated. The investigators estimated weighted RRs using random effects meta-analysis techniques.

Results:

The study cohort was comprised of 937 patients from six observational studies. Patients were 53 ± 12 years of age, and 80% were male. In 93% of the patients, bridge-to-transplantation was the indication for LVAD implantation. A continuous-flow (CF) LVAD was present in 361 patients (39% of patients). Mean left ventricular ejection fraction was 16 ± 6%. A significant proportion of patients were taking beta-blockers (59%), angiotensin-converting enzyme inhibitors (65%), and aldosterone receptor antagonists (44%). An ICD was present in 355 patients (38%). During a mean follow-up of 7 months, 241 patients (26%) died (16% in the ICD group vs. 32% in the no-ICD group). Presence of an ICD was associated with a 39% RR reduction in all-cause mortality (RR, 0.61; 95% CI, 0.46-0.82; p < 0.01). Approximately six patients (95% CI, 4.8-9.9) needed to be treated with an ICD for an average of 7 months to prevent one death. Among the subgroup of patients with CF-LVAD (n = 361), an ICD was present in 245 patients (68%), whereas 116 patients (32%) did not have an ICD. Mortality in the ICD group was 14% compared with 25% in the no-ICD group. Therefore, ICD use was associated with an 11% absolute risk reduction and a 24% RR reduction with a statistically nonsignificant trend toward improved survival in these CF-LVAD patients (RR, 0.76; 95% CI, 0.51-1.12; p = 0.17). Data on infection were available for 839 of the 937 patients from five studies. The incidence of infection was significantly lower in patients with ICDs (18 of 293 patients) than in patients without an ICD (96 of 546 patients), 6% vs. 18% (p < 0.01).

Conclusions:

The study authors concluded that ICD use is associated with a significant reduction in mortality in LVAD patients; however, this effect was not significant in patients with CF-LVADs.

Perspective:

This is an important study, which sheds light on the effectiveness of ICDs in a field that continues to evolve. An important takeaway from this study is that larger randomized studies are needed to determine effectiveness of: 1) beta-blockers and other guideline-mediated therapy, and 2) ICDs in newer-generation LVAD patients with and without ventricular arrhythmias.